Hereinafter, the term “load support” is to be understood as a carrier dedicated to packing units such as pallets, containers, trays and the like. Load supports are used for generating load units and storage units, respectively. In this context, it is distinguished, in dependence on its function, between: load supports having a carrying function, such as pallets or workpiece carriers; load supports having carrying and enclosing functions, such as wire-mesh pallets or trays; as well as load supports having a carrying, enclosing, and closing function, such as a freight container.
For example, trays are employed in order to singularize packing units, which are stored in huge numbers on pallets within a high-bay warehouse, onto trays in a suitable manner, and these trays are then transported to a so-called tray warehouse, where they are provided on call for processing order-picking orders. In the international logistics, a packing unit, if a piece good is provided, is also called “Kollo” (plural “Kolli”; derived from the Italian “collo”). A packing unit is the smallest unit of a shipment of goods or an order-picking order. A package including twelve milk bags being welded to each other by a film exemplarily represents a packing unit.
In logistics, piece good designates everything which can be transported in one piece, such as boxes, loaded pallets, beverage boxes, nutrition batches, housewares, etc. Liquid loadings or gases which are pumped into, for example, a transporting vehicle without their own container are not piece goods. Sand, coal, corn and comparable solids are bulk cargo or soaking goods.
The present invention is applicable to piece goods.
The German patent application DE 103 13 576 A1 (which is the priority basis of EP 1 462 394 A2) discloses an order-picking system. In the order-picking systems pallets from a pallet warehouse are singularized automatically in a known manner by means of a depalletizing means by grabbing and soaking means into single packing units. Packing units singularized in this manner are subsequently stored in a tray warehouse which serves as buffer. These trays are generally formed flat and tray-like, and preferably have a surrounding rim. The trays have holes or openings in bottoms thereof which allow passage of a lifting device for lifting an article loaded on the tray. Lifting pins of the lifting device engage with the article through the openings in the tray from beneath, and lift the article in this manner out of the tray. Consequently, a rake takes the article and pushes the article onto a horizontal loading board. Then, the lift pins can be lowered again so that the emptied tray can be transported back into the tray warehouse.
In the prior art, such rakes are also designated pushers. A pusher allows movements by which articles are transported away. As soon as an article to be pushed or transported away has reached its predetermined position, a pusher, i.e. the rake, is actuated which pushes the article towards an unloading direction.
For pushing-off the article from a conveyer track so called rotating-arm sorters are known as well.
With the known rakes and pushers a problem arises in that a tray can always only be unloaded completely. Thus, for example, it is not possible to merely push single packing units or articles off the tray. Besides that, it is not possible to transport away only particular packing units from the tray, particularly if these particular packing units are surrounded by other packing units. For this reason, all packing units are typically placed on single trays individually, which in turn represents a high performance requirement for the warehouse system.
The German laid-open patent application DE 101 27 778 A1 shows a transporting device dedicated to circuit boards which are sometimes only 35 μm thick. In order to allow the circuit boards to be transported safely, the circuit boards are put into receiving containers which are similar to a tray. These trays comprise openings allowing rollers to engage therethrough, which in turn can be lifted and lowered. The circuit boards are either transported onto the trays or from the trays by means of the rollers. Each tray serves for receiving a circuit board. One roller can be driven. Several or all rollers can be driven.
U.S. Pat. No. 3,675,801 discloses an apparatus for conveying, handling, loading, and unloading of palletized materials.